The present invention relates to a fluid strut, such as a gas spring, which can be locked in an extended position with a frangible or breakaway plunger-type lock.
Fluid struts, also known as gas springs or cylinders, are frequently employed to assist in the opening and holding open of closures, covers, or lids for a variety of products, including vehicle hoods, hatchback lids, trunk lids, and, in some cases, doors. Their use facilitates the opening and holding open of such devices. They have found application in a variety of fields, including storage trunks in vessels, such as power boats, storage and office cabinets and lockers, and other environments in which relatively heavy closure doors are required to be opened easily and maintained in an open position. In some applications where the closure member is relatively heavy, for additional safety, it is desired to lock the strut in a mechanically locked position to prevent any accidental closure of the cover when accessing the storage or other compartment to which the closure member is attached.
U.S. Pat. No. 4,807,855 discloses one locking approach in which a spring-loaded plunger lock is employed to automatically lock the gas strut rod when in an extended position, preventing the inadvertent collapsing of the gas strut when in an extended position. Although this provides the desired safety feature, in the event the user inadvertently or otherwise fails to remove the lock and slams the cover, such as a vehicle hood, trunk lid, or the like, downwardly against the locking pressure, serious damage can occur to the structural part of the vehicle or other closure member involved.
Accordingly, there is a need for a strut system in which the strut can be locked in a fully open or extended position, preventing inadvertent closure of a closure member with which the strut is employed. The system should allow, upon application of a closing force above a certain level, the strut to overcome the locking feature and allow closure of the covered compartment without damage to the closure member.